Australia's wheat producers are facing increasing pressure on yields as climate variability reshapes production decisions, with frost playing an increasingly challenging role.
A new study from CSIRO, Australia's national science agency, shows changing climate conditions are extending and intensifying the window of time for risk of frost damage.
Frost can cause up to $360 million annually in wheat production losses with the study, supported by the Grains Research and Development Corporation (GRDC), showing that late spring frost and earlier heat continued to challenge producers.
Wheat is the major winter crop grown in Australia with sowing starting in autumn and harvesting usually occurring in spring and summer.
CSIRO lead author Dr Fernanda Dreccer said the study examined how well current best-practice management is performing.
"Growers have access to a range of strategies including cultivar selection and sowing time so crops flower within the optimal flowering period," said Dr Dreccer.
"That is the window where yield is maximised by balancing frost, heat and water stress, with adequate nitrogen fertilisation.
"But our study asked the question: what are the limits of these best management strategies under increasing climate variability?"
To answer this, the research team ran long-term simulations across the Australian wheatbelt at 83 locations using climate data dating back to 1970 and a wide range of wheat cultivars.
The results showed that even under these best management conditions, frost remained a major constraint on yield even when flowering occurred within the optimal window.
Dr Dreccer said the study also highlights how management decisions for growers can involve unavoidable trade-offs between competing climate risks.
"As seasonal conditions vary, attempts to avoid heat and drought can increase exposure of frost during sensitive stages, with impacts compounded by late spring frost and the biggest impacts occurring when frost and heat stresses co-occur," Dr Dreccer added.
Dr Dreccer said the findings show that while phenology (the study of recurring biological events in plant life cycles) remains a critical tool, it is no longer sufficient on its own, with yields still constrained despite advances in agronomy and cultivar selection.
"The results show that reducing crop sensitivity to frost can deliver meaningful gains, particularly in adverse seasons," she said.
Over the past two years Dr Dreccer and her team have been researching how best to build frost tolerance in wheat , with a focus on evaluating genetically diverse wheat lines across multiple environments, including sites in New South Wales, South Australia and Western Australia, to better understand frost damage and the conditions that drive it.
"As part of this work, we are also improving understanding of the environmental conditions associated with frost events, particularly the role of humidity and dew formation, which are key drivers of frost type and damage," she said.
"This highlights an important gap in current approaches, which often rely on air temperature alone and do not fully capture canopy-level conditions that influence whether damage occurs.
"While progress in managing frost has been slow, this improved understanding is helping to better assess risk and guide both agronomic strategies and the development of crops with reduced sensitivity during critical growth stages."
You can learn more about the research paper - Shifting prospects for wheat production: Long-term simulation-based insights under best management in Australia – here .
More on CSIRO's work on the effects of frost on wheat:
- Frontiers | Challenges in modelling the impact of frost and heat stress on the yield of cool-season annual grain crops
- Event-based frost and heat damage functions improve yield predictions of APSIM canola and wheat: formulation, calibration, and evaluation - ScienceDirect
